The present invention relates to an optical distance measuring apparatus that irradiates ranging light such as laser light on a measuring object, receives light reflected from the measuring object, and measures a distance up to the measuring object, and further, to a light receiving circuit configuration and a range finding control method.
Conventionally, as one of distance measurement methods, known is a distance measurement method of a TOF (Time of Flight) system for irradiating laser light on a ranging object, receives laser light reflected from the ranging object, and finds a time difference from an irradiation time of laser to a light receiving time of the reflected laser light to find a distance up to the ranging object. In the laser range finding apparatus, it is necessary to receive reflected laser light with high sensitivity. In some light receiving elements, a high-sensitivity photo diode called APD (Avalanche Photo Diode) is adopted.
The APD is a photo diode in which a phenomenon called an avalanche multiplication is used to improve light sensitivity. However, in the APD, a change in a multiplication factor may be large due to a change in a temperature to cause a distance detection error. JP-A-2010-286448 discloses a technique of an optical distance measuring apparatus that controls a multiplication factor due to a change in a temperature of the APD and performs temperature compensation for reducing a detection error.